1. Field of the Invention
This invention relates to a brazing material having a low melting point for use in a low temperature brazing, which is preferably used to braze aluminum materials having a low-melting point such as cast materials. The invention also relates to a method for low temperature brazing by using the brazing material.
2. Description of the Related Art
In brazing aluminum cast materials or die-cast materials which melt at 600.degree. C. or below, a brazing material having a low melting point thereby enabling a low temperature brazing usually is required. Besides, with a view toward energy savings, a brazing material is required that can braze flattening materials which have various melting points, at a temperature lower than a brazing temperature of Al--Si brazing material.
In brazing different metallic materials such as an aluminum material and an iron material at a high temperature, a brittle intermetallic compound is produced, which deteriorates the strength of the brazed portion. Thus, in order to suppress the intermetallic compound, a brazing material that enables a low temperature brazing is desired.
Conventionally, as a brazing material which melts at a low temperature, brazing materials containing a large amount of Zn, such as a Zn-base alloy, a Zn--Al alloy or a Zn--Si--Al alloy, have been used.
The above-mentioned brazing materials containing a large amount of Zn has advantages that they enable a low temperature brazing because the melting point is lower than that of an Al--Si alloy. However, the large amount of Zn causes a lack of wetting property of the brazing material on a base material, which results in a brazing defect at the brazed portion, thereby causing leakage.